As said in the title, I need some good lowering springs to go with my shocks (not ready to go full coilover just yet). So here's the breakdown, my car is a 1986 Corolla GTS and (IDK if this will help) I'm running 15 inch Enkei 92s with 205s and Kumho Ecstas. I can't find much info on the 5-way adjustable Illumina shocks. Any advice would help!

Damper length will dictate spring length to some degree. If your dampers are 'full length' then fitting a lowered spring will mean that the spring will come loose at full extension, maybe not too much of a problem. Another bigger issue will be that the damper is likely to bottom out and when this happens the valving gets damaged, the handling will also suffer severely once bottomed out.I once bought a complete damaged AE86, it had hit a high kerb due to "uncontrollable understeer" it had bent the front chassis leg. Upon inspection of the suspension from the damaged corner I found a full length Koni damper without bump stop mated to a 8kg spring, the Koni valving was smashed up.The shorter spring combined with a lowered front centre of gravity (no RCA's were fitted) ensured that weight was transfered over the front corner to compress the spring just enough to bottom the damper and at this point the suspension went solid, terminal understeer was the result.

Illumina's were a very popular choice for upgrade shocks in the days before store bought coilover suspension became available. I think OST used them before he went with the HTS full stroke inserts ? General rule of thumb seems to be if you are not lowering more than an inch, full stroke inserts are OK. But if you are lowering more than one inch you should consider using a "short stroke" inserts.

Of course the spring rate has a lot to do with the shocks you choose if you want to avoid the type of problems outlined in the post above. Lowering springs with a few tightly wound coils at one end will make sure the springs remain captive. But if you want to use short "RACE" type springs with high dorifto rates, you will definitely need short stroke shocks.

Cheers... jondee86

Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

There is a difference between a "lowering" spring, and a performance spring. I've had springs wound for me that were about 2.5 x stiffer then the stock springs, but they rode @ stock ride height. Now the problem.... as totta corolla mentions the spring can come loose, not because it is "lower" although "lower" spring will also come loose, but because the new spring rate requires a new shorter length which will be a bit loose between the spring seats at full open - not good.

What I did to fix this issue was to borrow a bit of 1950's technology by installing limiting straps

I used a 2" wide, 5' long section of ratchet strap. I cut a 5/8" hole in the center, and then removed the dust seal, and draped the strap over the spring seat. I then added 2 stanless steel hose clamps to the bottom of the strut - just under the lower spring seats. Now, I had a friend compress the shock till I had about 1/2" of preload on the spring. Then I fed the straps through the SS hose clamps and tightened the clamps. This held the spring in place, and the strap stayed out of the way the rest of the time.... see photo above

That makes sense. I'm looking at lowering probably 1.5 inches but more importantly, I need to figure out the spring and damper rates. Based on your guys's advice, it'll probably better to hold off for now so I can get/make proper coilovers/separate rear since I also plan on autocrossing it. Thanks for your help!

*Disclaimer: i bought a used set so its possible they were worn out. Fwiw they werent cut and the condition of the appearance was fair.*

Anyhoo, the drop ended up being about 1.8" (possibly more) from stock. The sprng rates were 3/2.8k f/r. A low ride height with low apring rates is a bad combination... I was hitting bump stops... Yes they can be cut...

For comparison i had megan springs way back. 4.5/4k f/r rates iirc. In the real world the megan and espelir springs have a similar ride height. However with megan no bump stock contact because higher spring rate.